In what type of operation may a commercial pilot act as pilot-in-command and receive compensation for service, although not regulated by 14 CFR part 119?

A commercial pilot can act as pilot-in-command and receive compensation for service in a specific type of operation known as "nonstop flights within a 25 statute mile (SM) radius of an airport" that are not regulated by Part 119 of the Federal Aviation Regulations. This operation generally refers to flights that do not leave a relatively short distance from an airport, where certain requirements for larger operations, including those outlined in Part 119, do not apply.

The FAA recognizes that these types of flights are low-risk and can be conducted without the stringent oversight required for other commercial operations, allowing pilots the opportunity to operate without the additional regulatory burden. This is particularly relevant for operations like training flights, aerial tours, or certain agricultural missions, where flights are typically brief and operated in close proximity to the departure point.

The other options fall outside this specific regulation scope or involve greater distances or types of service that require adherence to stricter regulatory frameworks, such as charter operations or scheduled passenger services.